Semiconductor light emitting devices such as light emitting diodes and laser diodes are known. In semiconductor light emitting devices, improvement of heat dissipation is desired. For instance, due to heat generation, the resistance of the semiconductor crystal around the electrode may be decreased and locally form a path where the current easily flows. In this case, for instance, the decrease of light emission uniformity and the crystal degradation are more likely to occur. Furthermore, in a semiconductor light emitting device including a wavelength conversion layer made of e.g. phosphor, the temperature increase of the wavelength conversion layer may change the characteristics of the wavelength conversion layer.